Rotary pump for pumping viscous slurry



June 6, 1967 A. BENTON ETAL 3,323,464

ROTARY PUMP FOR PUMPING VISCOUS SLURRY Filed Dec. 50, 1965 2Sheets-Sheet 2 INVENTORS.

Low; 4). BEA/TOM gaaser M ZAMae-RF Arrows? United States Patent3,323,464 ROTARY PUMP FOR PUMPING VISCOUS SLURRY Louis Arnett Benton,Middlesex, and Robert Morrison Lambert, North Piainfield, N.J.,assignors to Johns- Manville Corporation, New York, N.Y., a corporationof New York Filed Dec. 30, 1965, Ser. No. 517,710 3 Claims. (Cl.103-103) This invention relates generally to rotary pumps and morespecifically to rotary pumps adapted to pump relatively viscous slurriescontaining fibrous materials.

In certain so-called wet process textile operations it is often desiredto pump slurries of fibrous materials, such as asbestos, rayon, etc. ina manner in which the integrity of the fibers is preserved. One of thedisadvantages of a great many slurry pumps, particularly those of themulti-vane type, is that the solid constituents of the slurry aresheared as they come into contact with the stationary wall defining thepump body cavity. Additionally, the impeller vanes in such pumps aresuch that they cause fibers to be entangled and/or to rope. As aconsequence, such pumps require considerable cleaning and maintenanceand are considered to be inefiicient for pumping fibrous slurries.

Accordingly, a primary object of the present invention is to provide animproved pump which overcomes the disadvantages of the slurry pumpsdescribed above.

Another object of this invention is to provide an improved pump which isespecially adapted to pump relatively viscous slurries containingincreased amounts of fibrous material.

Briefly, a slurry pump of the character described and constructed inaccordance with the instant invention comprises: a pump casing defininga central cavity for encasing a rotary impeller and a tangentialdischarge outlet, with the rotary impeller having an essentially radialcentral passage chamber and radial discharge ports defined by a pair ofsidewalls and bridging members bridging the sidewalls of the impeller,whereby the slurry being pumped is substantially confined within thechamber and out of major contact with the surfaces defining the centralcavity of the casing. In essence, the impeller defines a rotating cagehaving two generally diametrically opposite doors (discharge ports)which alternately present material for discharge to the discharge outletof the pump casing. The passage chamber is substantially clear of anyprotuberances or encumbrances on which the fibers may be caught orentangled. The bridging members essentially define chords across thecircle generated by the sidewalls of the impeller to contribute to theradial flow of the material through and from the passage. In preferredembodiments, the bridging members are laterally spaced a distance whichcorresponds substantially to the diameter of the inlet opening into thepassage chamber, which distance is less than the length of the chordformed by each of the bridging members.

Further objects and advantages of the present invention will be apparentin view of the specification set forth hereinafter.

In the drawing, wherein like numerals designate like parts:

FIG. 1 is a cross-sectional elevational view of a pump constructed inaccordance with this invention;

FIG. 2 is a cross-sectional elevational transverse view taken along line2-2 in FIG. 1;

FIG. 3 is an isometric view of the rotary impeller employed in the pumpshown in FIGS. 1 and 2; and

FIG. 4 is a front view, partially broken away, of an alternate form ofrotary impeller.

In the embodiment of the invention illustrated in FIGS. 1 and 2, thepump, generally designated by the numeral 10,

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includes sidewalls 12 and 14 and the peripheral wall 16 forming astationary casing 18. The casing 18 defines a central cavity 20 forenclosing the rotary impeller 22. The impeller 22 is supported onrotatable shaft 24 and is secured for rotational movement therewith bysuitable means, such as key member 28 extending through hub portion 30.

The rotary impeller 22 comprises a pair of parallel and spaced sidewallmembers 32 and 34 which are in planes normal to a plane extendingthrough the axis of rotation 26 of the impeller 22. The sidewall members32 and 34 may be considered to define respective parts of the front face33 and the rear face 35 of the impeller 22. The sidewall members 32 and34 are bridged by bridging members 36 and 38 and together therewithdefine a central passage chamber 40 for confining the slurry to bepumped within the impeller 22. As can be seen in FIG. 3, the terminaledges 42 and 44 of bridging members 36 and 38 together with the arcuateportions 46 and 48 of sidewalls 32 and 34 respectively, intermediate thebridging members 36 and 38, define outlet ports 50 and 52 from chamber40. The bridging members 36 and 38 also serve as guides for guiding theslurry through the chamber 40 and toward the outlet ports 50 and 52. Thesidewall member 32 defines an inlet port 54 for introducing the slurryto be pumped into chamber 40.

In a preferred embodiment, as illustrated in FIGS. 1 and 2, the sidewallmembers 32 and 34 are discs which form full circles and thus contributeto the dynamic balance of the impeller 22. However, in a less preferredembodiment, the peripheral arcuate portions, or area segments ABC andABC', may be omitted. An important aspect of this invention is that ofdefining a passage chamber 40 within the impeller 22 in an arrangementwhereby contact of the slurry, as it is rotated by the impeller 22, withthe walls 12, 14, and 16, is minimized. Consequently, in preferredembodiments, the bridging members 36 and 38 form chords AC and AC acrossthe circles generated by the rotation of the sidewalls, which chords areof a length greater than the lateral spacing S between the bridgingmembers 36 and 38. In other words, the chords AC and AC' are at least aslong as and preferably longer than the outlet port dimensions which aretransverse to the axis of rotation. Such an arrangement also imparts anessentially radial motion to the slurry as it discharges from theimpeller. This deters tangling of the fibers and choking or blocking ofthe pump.

In FIG. 4 is shown a modified form of impeller. The bridging or guidemembers 136 and 133 are modified, in that they are slightly curved.However, the members 136 and 138 still basically define chordsand'together with the sidewalls 32 and 34 define essentially radialdischarge ports 150 and 152 for chamber at peripheralarcuate portions ofthe sidewalls 32 and 34.

In preferred embodiments of the invention, the terminal edges of thebridging or guide members are closely adjacent the circular wall 16 orcasing 118 to deter any substantial amount of fibrous slurry frompassing therebetween and becoming entangled with other edges. Also,essentially there are no leading edges of an impeller vane, as commonlyknown, to catch or entangle the fibers of the slurry or to create undueturbulence within the slurry being pumped. The esentially closedconstruction provides an arrangement wherein the moving fibers aremostly in contact with the moving surfaces of the impeller sidewalls andof the bridging guide members, as opposed to any stationary surfaces ofa pump casing, and thus minimizes any shearing action. The essentiallyradial motion through passage chamber defined by the chord formingbridging members deters the violent mechanical forces generated by theusual radial type impeller vanes and which forces cause dewatering orsegregation of fibrous slurries.

Slurries containing 8% solids (fibers), by weight, and at pressures upto 25 psi. have been efiiciently pumped, without presence ofentanglement of the fibers, with pumps embodying the features of thepresent invention. In contrast, centrifgual pumps which have beenheretofore available are only capable of pumping slurries which contain,as an average, 3 to 4% solids. Some pumps have been capable of pumping6% solid slurries, but the solid contents in these slurries were notpredominantly fiber.

In some instances, some increase in contact between the solid particlesof a pumped slurry and stationary portions of the pump may be tolerated.In such cases, as for example, when pumping slurries containingcellulosic fibers, one or the other of the impeller sidewall members 32and 34 may be omitted. However, if a sidewall is omitted, it ispreferred that the sidewall member 32 be omitted. Since sidewall member32 defines the inlet port 54, its omission will result in less of anincrease of exposed stationary surface area than the omission ofsidewall member 34. While the members 36 and 38, in such arrangements,no longer bridge between two sidewall members of the impeller, they dobridge the lateral space between the remaining sidewall of the impellerand a side wall of the pump casing.

In the preferred embodiments of the invention, the impeller 22 has beendisclosed in the drawings as comprising relatively thin bridging members36 and 38. However, it will be understood that the impeller 22 may befabricated as a single casting and that arcu-ate portions ABC and ABCmay be completely filled. An important aspect of this invention is thata central passage chamber 41), for confining the slurry and minimizingcontact of the slurry being pumped with stationary portions of the pump,be defined.

While specific embodiments of the present invention have been set forthand described in detail herein, it will be understood that variouschanges and modifications may be made therein without departing from thespirit of the invention or the scope of the appended claims.

What we claim is:

1. In a liquid slurry pump adapted to pump viscous slurries:

(a) a stationary casing including a peripheral wall portion and defininga central cavity enclosing a rotary impeller,

(b) said impeller having front and rear faces, an axis of rotation, andcomprising a central passage chamber defined by a pair of transversesidewall members and bridging members interconnecting said sidewallmembers,

() said chamber having an inlet which is coaxial with said axis ofrotation and a pair of outlets which are generally diametricallyopposite about said axis of rotation, and

((1) each of said bridge members forming a chord extending substantiallyacross the circular portion of said cavity and closely adjacent to saidperipheral wall portion to substantially deter passage of the solids ofsaid slurry between said bridging members and said peripheral wallportion, and said front and rear faces of said impeller each having atleast a portion closely adjacent to their respective sidewall portion ofsaid casing to deter passage of said solids therebetween.

2. A slurry pump adapted to pump fibrous slurries,

which pump comprises:

(a) a stationary casing including a generally cylindrical central cavitydefined by a pair of sidewalls and a peripheral Wall, said casingdefining a discharge outlet, and a rotary impeller, having front andrear faces and an axis of rotation, and being encased by said casing andcomprising:

(1) a pair of parallel sidewall members traversing said axis ofrotation,

(2) spaced apart and generally parallel bridging members bridging saidsidewall members,

(3) each of said bridging members forming a chord extendingsubstantially across the circular portion of said cavity,

(4) each of said bridging members also having its terminal portionsclosely adjacent to said peripheral wall to substantially deter passageof the fibers of said slurry between said terminal portions and saidperipheral wall, and said front and rear faces of said impeller eachbeing closely adjacent to a respective sidewall portion of said casingto deter passage of said fibers therebetween,

(5) one of said sidewall members defining an inlet which is coaxial withthe axis of rotation of said impeller.

3. In a liquid slurry pump adapted to pump viscous slurries,

(a) a casing including a side wall portion and a peripheral walldefining a central cavity having a circular portion and enclosing arotary impeller,

(b) said impeller having front and rear faces, an axis of rotation andcomprising a central passage chamber defined by a transverse sidewallmember and spaced-apart bridging members extending across and beingsecured to said sidewall member,

(c) each of said bridging members forming a chord extendingsubstantially across the circular portion of said cavity and having itsterminal portions closely adjacent to said peripheral wall tosubstantially deter passage of the solids of said slurry therebetween,and said front and rear faces of said impeller being closely adjacent toa respective sidewall portion to deter passage of said solidstherebetween.

References Cited UNITED STATES PATENTS 1,577,110 3/1926 Collins 230-127FOREIGN PATENTS 507,182 12/1951 Belgium. 155,134 1883 France. 954,66912/1956 Germany. 240,387 10/1925 Great Britain. 247,106 2/ 1926 GreatBritain. 102,102 11/ 1923 Switzerland.

DONLEY J. STOCKING, Primary Examiner.

HENRY F. RAD-UAZO, Examiner,

1. IN A LIQUID SLURRY PUMP ADAPTED TO PUMP VISCOUS SLURRIES: (A) ASTATIONARY CASING INCLUDING A PERIPHERAL WALL PORTION AND DEFINING ACENTRAL CAVITY ENCLOSING A ROTARY IMPELLER, (B) SAID IMPELLER HAVINGFRONT AND REAR FACES, AN AXIS OF ROTATION, AND COMPRISING A CENTRALPASSAGE CHAMBER DEFINED BY A PAIR OF TRANSVERSE SIDEWALL MEMBERS ANDBRIDGING MEMBERS INTERCONNECTING SAID SIDEWALL MEMBERS, (C) SAID CHAMBERHAVING AN INLET WHICH IS COAXIAL WITH SAID AXIS OF ROTATION AND A PAIROF OUTLETS WHICH ARE GENERALLY DIAMETRICALLY OPPOSITE ABOUT SAID AXIS OFROTATION, AND (D) EACH OF SAID BRIDGE MEMBERS ORMING A CHORD EXTENDINGSUBSTANTIALLY ACROSS THE CIRCULAR PORTION OF SAID CAVITY AND CLOSELYADJACENT TO SAID PERIPHERAL WALL PORTION TO SUBSTANTIALLY DETER PASSAGEOF THE SOLIDS OF SAID SLURRY BETWEEN SAID BRIDGING MEMBERS AND SAIDPERIPHERAL WALL PORTION, AND SAID FRONT AND REAR FACES OF SAID IMPELLEREACH HAVING AT LEAST A PORTION CLOSELY ADJACENT TO THEIR RESPECTIVESIDEWALL PORTION OF SAID CASING TO DETER PASSAGE OF SAID SOLIDSTHEREBETWEEN.